1. Field of the Invention
The present invention relates to a valve operating system in an internal combustion engine, and particularly, to a valve operating system in an internal combustion engine including an electric actuator which enables a power to be applied in an valve-opening direction to an engine valve that is biased in a valve-closing direction by a spring.
2. Description of the Related Art
Such a valve operating system is conventionally already known, for example, from Japanese Patent Application Laid-open No. 3-92520 or the like.
In the above known system, however, the engine valve is opened and closed only by the electric actuator. For this reason, the operational characteristic of the engine valve can be changed depending on the operational state of the engine, but the actuator must exhibit a driving force corresponding to a maximum lift amount of the engine valve, resulting in an increased amount of electric power consumed in the actuator.